The present invention reletes in general to devices for thermal expansion compensation, and in particular to a new and useful apparatus which can compensate for linear thermal expansion between elements which are connected together and which may expand or contract with respect to each other.
Because of the fact that the coefficient of thermal expansion of an explosive (in the case of explosives associated with TNT the coefficient of thermal expansion .alpha.=50 to 60.times.10.sup.-6 dgr.sup.-1) is roughly double that of the shell material, which is usually metal and most commonly aluminum (coefficient of thermal expansion .alpha.=23.8.times.10.sup.-6 dgr.sup.-1), under the influence of temperature, linear differences occur between the explosive member and the shell.
In other words, when there is a temperature increase, the explosive member expands more than the shell, with the result that the shell and cover plate deform and stress cracks may appear in the explosive member.
When temperature drops, on the other hand, the explosive member shrinks more than the shell. This can result in the base of the lining coming loose from its abutment, which may consist, for example, of a ring screwed into the shell or the inner flanged edge of the shell. The lining is then no longer adequately attached, and can be shaken loose from the explosive member by, e.g. environmental incluences, shock or vibration, for example.
It can also happen, however, that the liner becomes skewed inside the shell, so that when the explosive member shrinks, considerable stress is created between the lining and the explosive member that can lead to a gap between the lining and the explosive member or to cracks in the explosive member.